This invention relates in general to lighting for stage productions and more particularly to image projection onto a stage.
Lighting for stage productions, especially lighting for large scale productions for mass audiences such as rock concerts that require highly charged, intense atmospheres, is generally based upon a dual lighting system. The basic lighting is the spotlight that illuminates the performers as they move around the stage. In backup tandem with the spotlight is an image-casting lighting system that projects onto the stage continuous moving images that are aimed at a display area of the stage. The present system of moving image projection uses the common film projector used in movie theaters.
The spotlight luminaire and the associated beam modification devices such as the lens and an optional color wheel are presently mounted in a single spotlight housing that is compact and of such a weight that it can be moved about horizontal and vertical axes that enable the spotlight to cast its beam upon and follow a performer about the stage. In large scale stage productions exemplified by rock concerts the movements of the housing for the spotlight is motor driven in conjunction with a computer program created for the particular show so that the beam is moved about the stage in predetermined areas. The performer in turn has been rehearsed to move about the stage in synchronization with the beam so that what appears to be spontaneous movements by the performer are in fact based upon the performer anticipating the automatic placements of the spotlight.
In contrast with the dynamic flow of the performer and the spotlight beam is the static situation of moving image projection. Film projectors are much too heavy to be placed in a housing that can be moved either horizontally or vertically much less a combination of both. In present stage productions a film projector is placed upon a table, and a luminaire casts the beam of the moving images through the moving film in a manner known in the art onto a stage display, generally a rear surface of the stage. The static nature of such a moving image display cannot be overcome by the moving images themselves since the display itself must be stationary. This static effect is not in harmony with the effect of highly charged energy that accompanies and enhances the music of rock concerts.
A recent innovation in image display is the digital micromirror device or deformable mirror device (DMD) that is in the general field known as the spatial light modulator (SLM). In general, the DMD is a Micro-Opto-Electro-Mechanical Structures (MOEMS) device that is used for a high quality projection. An early version of the DMD is described in U.S. Pat. No. 4,662,746 issued to Hornbeck on May 5, 1987. This invention describes an array of mirror elements, described therein as pixels, that are cantilevered by addressing electric circuitry and resulting electrostatic force that induces a mirror cell position that reflects a light beam from a direction away from a display to a mirror cell position that directs a reflected digital light beam onto a display. This patent is incorporated by reference into the present application.
Improvements to the early DMDs are described in particular in U.S. Pat. No. 5,083,857 issued to Hornbeck on Jan. 28, 1992, U.S. Pat. No. 5,535,047 issued to Hornbeck on Jul. 9, 1996, and U.S. Pat. No. 5,600,383 issued to Hornbeck on Feb. 4, 1997, which describe a DMD pixel array that includes each mirror attached to an underlying yoke connected to torsion hinges. These named patents are incorporated by reference into the present application and made a part of herein.
The entire mirror array of the DMD is basically of one unit with the cell mirrors being addressed by circuitry and electrodes. The mirrors are bistable and movable at digital rates far in excess of the critical flicker frequency (CFF) of the human eye. In the DMD projection system, the human eye acts as the final digital signal to analog signal converter for transmission to the human brain. Electronic circuitry and receiver, converter, memory, and processor coupled to the DMD are described in U.S. Pat. No. 5,079,544 issued to DeMond and Thompson on Jan. 7, 1992 and in U.S. Pat. No. 5,192,946 issued to Thompson and DeMond on May 9, 1993. These patents are incorporated by reference into and are made a part of the present application.
In addition, U.S Pat. Nos. 4,441,791; 4,710,732; 4,596,992; 4,615,595; 4,662,746 issued to Hornbeck showing deformable digitally addressable mirrors are incorporated by reference into the present application.
U.S. Pat. No. 5,658,063 issued to Nasserbakht on Aug. 19, 1997 describes a video projection device for projecting video images onto a surface. A discussion therein of FIG. 8 therein, lines 43-67 and page 8, lines 1-35, describes a video projection system that includes a digital light processing system as described in U.S. Pat. No. 5,192,946, which has already been incorporated by reference herein.
Other patents concerning DMD technology that have general relationship to the present invention are as follows:
U.S. Pat. No. 4,566,935 on Jan. 28, 1986
U.S. Pat. No. 4,615,555 issued on Oct. 7, 1986
U.S. Pat. No. 4,662,746 issued on May 7, 1987
U.S. Pat. No. 5,583,688 issued on Dec. 10, 1996, 1987
Patents concerning DMD technology that have general relationship to the present invention in the area of optics are as follows:
U.S. Pat. No. 5,105,299 issued on Apr. 14, 1993
U.S. Pat. No. 5,311,349 issued on May 10, 1994
U.S. Pat. No. 5,467,146 issued on Nov. 14, 1995
U.S. Pat. No. 5,548,443 issued on Aug. 20, 1996
U.S. Pat. No. 5,612,753 issued on Mar. 18, 1997
U.S. Pat. No. 5,670,977 on Sep. 23, 1997
U.S. Pat. No. 5,680,257 issued to Oct. 21, 1997
U.S. Pat. No. 5,706,061 issued on Jan. 6, 1998
U.S. Pat. No. 5,796,526 issued on Aug. 18, 1998
Some of the basic advantages of DMD technology are being fully digitized, having greater resolution than the prior art, being highly adaptable to large scale displays, cost effective, and light weight.
Although all the listed advantages of DMD technology are highly desirable, the fact that the DMD is light weight makes it particularly suitable for replacing the heavy weight film projector used for stage productions. The DMD along with a light source, a coloring device and a lens system can be mounted in a housing light enough to be rotated, that is, panned and tilted, about one or two axes either by hand or by a driver to create a moving image beam that is as mobile and as directable as the spotlight beam.
Coloring of a white light source can be achieved in the digitized light beam by any of several means known in the art. Various types of color wheels can be used in a manner known in the art. In addition, a spinnable color wheel having a wide range of colors can be digitized at a greater rate than the CFF of the human eye. Coloring of a digitized light beam can also be achieved by a single laser or a three-way laser of the three primary colors. Such coloring techniques are described in U.S. Pat. No. 5,079,544 and U.S. Pat. No. 5,192,946, page 14, line 30-49, earlier incorporated herein and made a part of the present application. Coloring of a single laser light beam can be achieved by digitizing the single laser at a frequency less than the color integration time for color for the human eye. A discussion of the integration time for the human eye for color, which differs from the CFF of the human eye, is set forth on page 12, lines 61-68, of U.S. Pat. No. 5,192,946.
Other structures can be used to add coloring to the DMD light display systems. Beam-splitting prisms can split white light into various components of the visible electromagnetic spectrum as described in the following paper: xe2x80x9cDisplay System Architectures for Digital Micromirror Device (DMD(trademark))Based Projectors,xe2x80x9d by James M. Florence and Lars A Yoder, SPIE, Vol. 2650, pp. 193-208 (1996), which is incorporated into and made a part of the present application.
Technical papers describing DMD technology are as follows:
xe2x80x9cDigital Light Processing(trademark) for High-Brightness, High-Resolution Applications,xe2x80x9d by Larry J. Hornbeck, Texas Instruments 1997, Product # DPL-0030, Digital Video Productsxe2x80x9d
xe2x80x9cDigital High-Brightness, High-Resolution Applications,xe2x80x9d by Larry J. Hornbeck, in Electronic Imaging, EI, Projection Displays III, co-sponsored by ISandT and SPIE, 10-12 Feb. 1997, San Jose, Calif. The above articles are incorporated into and made a part of the present application.
The present invention provides a light display system for projecting onto a stage display a digitally generated light beam having the optical effect of a continuous moving image in which objects move that includes a housing rotatable about a horizontal axis and a vertical axis, a deformable mirror device (DMD) having a surface comprising an array of deformable mirror cells, or pixel mirrors, or pixels, the DMD being mounted in the housing. A lamp is mounted in the housing for directing a beam of light to impinge upon the pixel surface of the DMD. A first driver rotates the housing about a horizontal axis, and a second driver rotates the housing about a vertical axis. Digital control signals to the DMD activate selected pixels of the DMD to reflect digital imaged light beams to the stage display. The light source can be either standard lamps or arc lamps or lasers. Color is achieved by a color wheel, by lasers, or by chromatic prisms or a combination of chromatic prisms and a color wheel.
Analog data when that is the basic available data is converted to digital data at a video signal analog-to-digital image data converter. The digital image data is then prepared for application to a DMD at a DMD digital formatter. Once digital formatting is accomplished, control signals are directed to the addressing circuitry for the DMD. The DMD includes a mechanical interface and digital optics, which includes a plurality of bistable pixels. Control signals written to the addressing circuitry directs the DMD mechanical interface that controls the bistable rotations of the array of pixel mirrors that comprise the surface of the DMD. In addition the optics include color combinations associated with a color wheel or beam-splitting prisms mounted in the housing are created as directed by signals from the computer that are written to the addressing circuitry including each Static Ram (SRAM) of each DMD in synchronization with the rotations of the pixel mirrors.